d = struct('a','1','b','2')

d.('a')
d.('b')

d.('b')='9'

d.('c')='3'

d=struct('b', '9','c', '3', 'a', '1')
d=rmfield(b,'9')

d=struct()

%% 創(chuàng)建數(shù)組
x = 10;
Y = double(x);  % 轉(zhuǎn)換為double型數(shù)組
y = 10;

%% 查看數(shù)據(jù)類型
class(Y)

% 創(chuàng)建字符串
str = "Hello, world"
>>> str = 
"Hello, world"

% 創(chuàng)建字符串數(shù)組
str = ["Mercury" "Gemini" "Apollo";
       "Skylab" "Skylab B" "ISS"]
       
>>> str = 2x3 string
    "Mercury"    "Gemini"      "Apollo"
    "Skylab"     "Skylab B"    "ISS" 
  
% 傳入?yún)?shù)轉(zhuǎn)換為字符串數(shù)組
str = string(A)   % 將輸入的數(shù)組轉(zhuǎn)換為字符串數(shù)組
str = string(A, datetFmt)   % 將傳入的A轉(zhuǎn)換指定的時間格式，所以傳入的A是datetime或者duration

% A表示的是字符向量
A = 'Four score and seven years ago'
c = size(A)   
>>> c = 1×2

     1    30
str = string(A)
s = size(str)
>>> s = 1×2

     1     1
% 通過strlength可求的str中字符串的長度
n = strlength(str)
>>> n = 30


% 轉(zhuǎn)換元胞數(shù)組
A = {'Mercury','Gemini','Apollo';...
     'Skylab','Skylab B','ISS'}
>>> A = 2x3 cell
    {'Mercury'}    {'Gemini'  }    {'Apollo'}
    {'Skylab' }    {'Skylab B'}    {'ISS'   }
str = string(A)
>>> str = 2x3 string
    "Mercury"    "Gemini"      "Apollo"
    "Skylab"     "Skylab B"    "ISS" 
    
% 轉(zhuǎn)換表示數(shù)字的字符串
str = ["256","3.1416","8.9e-3"]
>>> str = 1x3 string
    "256"    "3.1416"    "8.9e-3"
X = double(str)
>>> X = 1×3

  256.0000    3.1416    0.0089
Y = str2double(str)
>>>Y = 1×3

  256.0000    3.1416    0.0089

%% 創(chuàng)建一個字段的結(jié)構(gòu)體
field = 'f';
value = {'some text';
         [10, 20, 30];
         magic(5)};
s = struct(field,value)

% 查看每個元素在內(nèi)容
>>> ans = 
'some text'
ans = 1×3

    10    20    30

ans = 5×5

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

%% 創(chuàng)建多個字段的結(jié)構(gòu)體
field1 = 'f1';  value1 = zeros(1,10);
field2 = 'f2';  value2 = {'a', 'b'};
field3 = 'f3';  value3 = {pi, pi.^2};
field4 = 'f4';  value4 = {'fourth'};

s = struct(field1,value1,field2,value2,field3,value3,field4,value4)
>>> s=1×2 struct array with fields:
    f1
    f2
    f3
    f4
% 輸出上述字段的結(jié)果
>>> s(1)
ans = struct with fields:
    f1: [0 0 0 0 0 0 0 0 0 0]
    f2: 'a'
    f3: 3.1416
    f4: 'fourth'
>>> s(2)
ans = struct with fields:
    f1: [0 0 0 0 0 0 0 0 0 0]
    f2: 'b'
    f3: 9.8696
    f4: 'fourth'

%% 創(chuàng)建空字段的結(jié)構(gòu)體
s = struct('f1','a','f2',[])
>>> s = struct with fields:
    f1: 'a'
    f2: []
%% 創(chuàng)建包含元胞數(shù)組的字段
field = 'mycell';
value = {{'a','b','c'}};
s = struct(field,value)
>>> s = struct with fields:
    mycell: {'a'  'b'  'c'}

a = cell()
a = {}

C = {1, 2, 3}
>>> C=1×3 cell array
    {[1]}    {[2]}    {[3]}

C{4,4} = 44
>>> C=4×4 cell array
    {[       1]}    {[       2]}    {[       3]}    {0x0 double}
    {0x0 double}    {0x0 double}    {0x0 double}    {0x0 double}
    {0x0 double}    {0x0 double}    {0x0 double}    {0x0 double}
    {0x0 double}    {0x0 double}    {0x0 double}    {[      44]}

C = {'one', 'twC=2×3 cell array
    
>>> C=2×3 cell array
    {'one'}    {'two'}    {'three'}
    {[  1]}    {[  2]}    {[    3]}   

upperLeft = C(1:2,1:2)
>>> upperLeft=2×2 cell array
    {'one'}    {'two'}
    {[  1]}    {[  2]}

% 修改第1行 1，2，3列的值
C(1,1:3) = {'first','second','third'}
>>> C=2×3 cell array
    {'first'}    {'second'}    {'third'}
    {[    1]}    {[     2]}    {[    3]}

numericCells = C(2,1:3)
>>> numericCells=1×3 cell array
    {[1]}    {[2]}    {[3]}
    
numericVector = cell2mat(numericCells)
>>> numericVector = 1×3

     1     2     3

% 訪問元胞的值
last = C{2,3}
>>> last = 3

C{2,3} = 300
>>> C=2×3 cell array
    {'first'}    {'second'}    {'third'}
    {[    1]}    {[     2]}    {[  300]}

% 訪問數(shù)組中某一行的值并轉(zhuǎn)換為數(shù)值數(shù)組
nums = [C{2,:}]
>>> nums = 1×3

     1     2   300

myNum = [1, 2, 3];
myCell = {'one', 'two'};
myStruct.Field1 = ones(3);
myStruct.Field2 = 5*ones(5);

C = {myNum, 100*myNum;
     myCell, myStruct}
     
>>> C=2×2 cell array
    {[ 1 2 3]}    {[100 200 300]}
    {1x2 cell}    {1x1 struct   }
    
% 訪問元胞的內(nèi)容
C{1,2}
>>> ans = 1×3

   100   200   300
  
c{1, 2}(1, 2)
>>> ans = 2

C{2,1}{1,2}
>>> ans = 'two'